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The Pentagon approved an additional 1,000 troops to the region after a recent attack on commercial tankers in the Gulf of Oman that the US blames on Iran.

As war clouds loom over the Gulf, the question is: Will the US or its allies risk a pre-emptive strike on Iran and trigger a conflict? So far, the United States has sent positive signals, with its special envoy Brian Hook saying President Donald Trump's Iran policy is ultimately aimed at bringing Tehran to the negotiating table.

"No one should be uncertain about our desire for peace or our readiness to normalise relations should we reach a comprehensive deal," Hook said last month, briefing American lawmakers at a Congress panel. "We have put the possibility of a much brighter future on the table for the Iranian people," he told the House Committee on Foreign Affairs.

Successive US governments have resorted to pre-emptive strikes and regime change to further its interests. And the fear is, history could repeat itself again if the United States and Iran remain on a collision course.

Some in Congress have voiced concerns that US troop build-ups, sanctions pressure and heated rhetoric could accidentally pull the US into a military confrontation with Iran.

The Pentagon approved an additional 1,000 troops to the region after a recent attack on commercial tankers in the Gulf of Oman that the US blames on Iran.

Although many parties claim that a negotiated outcome remains very much on the table, there is the talk of a pre-emptive strike on Iran's nuclear facilities - especially in Israel - Iran's arch enemy.

Watch: US-Iran Tensions—War clouds loom over the gulf

But an attack on Iran's nuclear facilities could have consequences - some unforeseen - for the region at large. It could snowball into a prolonged conflict in which other regional actors - both state and non-state - could become involved.

The pro-strike lobby worries that Iran could further provoke by enriching uranium to a weapons-grade, enough to possess a nuclear bomb and a pre-emptive strike could prevent it. For the moment though, Washington is weighing its options.

Already, in the past few weeks, the US has dispatched warships to guard against threats to American interests in Iraq - and to deter Iran and its proxies.

But as a Brookings report suggests, a conflict would begin even if the US targets Iranian interests beyond its borders - for example, Iraq.

A pre-emptive strike on Shiite militias in Iraq or elsewhere in the region could push Iraq into another crisis and provoke Iran.

The Trump administration last year withdrew from the nuclear deal negotiated with Iran under President Barack Obama and began imposing layers of punishing sanctions on Tehran that have strangled its economy.

The US blames Iran for a number of attacks against American or Western interests in West Asia over the past few months, including on tankers near the Persian Gulf and a rocket attack near the US Embassy in Baghdad. Iran denies responsibility for the attacks.